{{- $style := default "default" (.Get "style") -}}
<span class="book-badge {{ $style }}">
  {{- with .Get "title" }}<span class="book-badge-title">{{ . | plainify }}</span>{{ end -}}
  {{- with .Get "value" }}<span class="book-badge-value">{{ . | plainify }}</span>{{ end -}}
</span>